You did a lot of things right and a few things wrong:
What I love is the style of each individual piece. You added some nice shelving, a cool fireplace, nice windows, each component looks great. The colors on those separate components also works out well.
However, when you put it all together, some things don't go together. The colors seem to conflict a bit. Taking one or two colors out and replacing them with a shade of another might help but it looks a little off (Just the green wall decor, the red table mat, the blue trim, and the brown ceiling are what I really notice. You also have like 3 different types of shelf all on one wall and it's just a bit cluttered.
The structure of the building itself is really nice though. They way the windows are separated, the way the trim is laid out and the placement of the slanted ceiling work very well. The flooring also looks nice with the border near the wall.
I like each part of it and the overall structure, but it could use a little more work. I also kinda want to see what the other parts of the house/exterior would look like but I know that you haven't built that yet. Maybe post an update? :D
8/10